Many vehicle seals are flexible to conform to vehicle glass to seal out the elements. The flexibility must be maintained over a wide range of temperatures. Moreover, the seal area in contact with glass requires a low coefficient of friction so that when glass is raised or lowered, the seal does not stick to the glass. While ethylene-propylene-diene monomer rubber (EPDM) has a suitable flexibility, it has a less than preferred coefficient of friction. In an attempt to reduce the coefficient of friction, the surface of ethylene-propylene-diene monomer rubber has been coated with polyurethane. However, the polyurethane coating is not particularly resistant to wear, which results in failure of the seal within a relatively short time. Attempts have been made to produce seals with polymeric coatings other than polyurethane; however such seals typically employ volatile organic solvents during the manufacturing process. Such volatile organic solvents have recently become the subject of governmental regulation.
It would be desirable to have a flexible, wear resistant seal, having a low coefficient of friction, and which is applied without volatile organic solvents.
The present invention provides novel laminate useful for seals, particularly for vehicle window seals that are both flexible and wear resistant and have a low coefficient of friction, preferably with an initial coefficient of friction below 0.5. The laminate comprises a rubber substrate and a polyolefin coating disposed on and adherent to the rubber substrate.
The invention also provides novel methods of making seals; such a-method comprises the following steps: providing a rubber substrate; then applying a powdered crystalline polyolefin to the rubber substrate, in an amount sufficient to form a continuous layer when melted; and then melting the powdered crystalline polyolefin to form a continuous polyolefin coating disposed on and adherent to the rubber substrate. The invention also relates to seals comprising: a polyolefin rubber substrate; and a continuous coating of fused polyolefin disposed on and adherent to the rubber substrate.